The International Steam Pages

Snowdon Mountain Railway #4, 'Snowdon'

Nigel Day reports on work on modernising a centenarian locomotive: (Pictures added 5th October 1999, position your mouse over them for the captions!). I have now added a further update (6th March 2000, with more pictures). The next update was on 18th December 2000.

Since around 1986 a systematic program of research, development and application has been applied to steam locomotives. Part of the reason for this was a desire to keep up with the 'new diesel locomotives. The first locomotive to receive attention was No.7 a 1923 superheated SLM locomotive. Although not a complete list of items is included the main ones include lubrication and draughting. This work has been later applied to other locomotives on the Welshpool and Llanfair, Isle of Man, Embsay, and two the standard gauge tanks. The draughting is to the lempor type and various other developments beyond.

By 1991 attention had turned to No.4 'Snowdon' a 1895 SLM product. This being an older machine than No.7 means that some features are less advanced like the suspension. It has received similar attention to No.7 and with other work carried out in due coarse.

By the November of last year authority for the locomotive to be converted to oil firing was given. This was brought about by a number of contributing factors. The main one is that within Britain the supply of suitable coal has reached a state where it was a choice between what type of black stones you could get. Currently the use of Polish coal is the only real option. Snowdon has tried oil firing before. The first attempt was to the Laidlaw Drew system. This proved only partially successful with heavy vibration and shortage of steam after Clogwyn where the steepest part of the line is. This system only lasted a few years before reconversion to coal. Another system was tried in 1990 but was wholly inadequate and never got beyond simple tests. With the development work carried out since then the stage was then set to try again.

No.4 was used because it is 'my engine' and thus control of the situation was possible as a test bed for the rest of the fleet.

Fueling up the hard way with oil firing controls centre right.

The work has involved a new design of burner which has no similarities to existing burner but uses first principles to atomise the fuel. Two burners are fitted to the rectangular firebox.

New firebox door with self closing flap.

A fire pan to support the burners and provide control of the highly modernised airflow arrangement. A piping system which conditions the atomising steam allowing for good air intake to the very restricted fire box which pro rata can handle a combustion rate approximately twice that of other systems of a comparable firebox size. The improved draughting system of lempor technology which has made the steaming rate exceed that of the Laidlaw system. Fuel tanks in the back of the cab. And last but not least a system of pipe work and controls which is simple with no computers or highly complex equipment. Once running the system can be all but controlled by one valve for the varying conditions.

Fireman's side view

Another view of the pipework

Test running started in the Spring. A number of modifications to the pipe work was necessary and air flow to make the system work. After only some 50 miles of testing, the locomotive has done over 97 return trips (1000 miles) to the summit with a high reliability factor. The benefits have been many. Cost of fuel is around 20% less than that of a coal burner. The engine is cleaner with no disposal of ashes or fire cleaning. No fire risk or spark throwing. Less labour in fuelling etc. Some of these benefits are hard to cost but are they large. The problems of the former system are not present and with a few minor improvements the stage is set for further conversions in due coarse.

First successful trip to the summit, within 2 days it was on passenger trains.

Ready for another trip - note Lempor chimney

It is relevant that DMSTS who have carried out the conversion under contract have now the technology to convert any locomotive successfully to oil firing including standard gauge locomotives once a suitable locomotive is put before use. Please contact use through by email ( or telephone +(44) 128 687 1305

Nigel adds (6th March 2000) This winter little has been found necessary to be done. One of the cones in the burner has been changed to a harder steel but all the research work in the new design of burner has worked out well. Improvements have been made to the airflow and draughting which are to be tested in the next few weeks. No adverse effects have been found on the boiler due to the conversion. Last season the locomotive completed some 117 trips with only one minor hickup. The is a saving of fuel costs of between 25 and 30% compered with a coal burner. SMR still plans to make further conversions of their locomotives and fittings are being installed on another locomotive prior to the conversion. Talks with several potential locomotive owners other than SMR for further conversions are on going.

rear view

front view

cab layout

cab view

Nigel adds: (18th December 2000) In this season (2000) two main items have been tackled with respect to the locomotive. Firstly many of the footplate crews have been taught how to fire the locomotive. The crews have generally taken to it well. there has been many comments even from the diesel drivers that if this was how steam locomotives were when they were on them then they would not have wanted to go on the diesels. The lack of hard preparation and disposal is also much appreciated. It has been easy to keep the locomotive in a very presentable state similar to that of the showman's traction engines. This presentation of the locomotive has given great pleasure to many people and it is often overlooked that the fuel has been changed.

The second factor is that much research has been done in how to improve the airflow and air/fuel mixing, this has produced some amazing revelations to the accepted schemes used on other locomotives. The route cause of vibrations for oil burners is now well understood. A number of other very interesting lines of research have been investigated and practical methods of application are now being worked out. In addition to the lines of research directly related to the oil firing system it has been obvious that some of the lessons learnt have a direct bearing on how to improve other items like the draughting. The 10% or greater saving in fuel consumption achieved this spring has been maintained and more savings are expected next year.

During the summer visitors to see the locomotive have come from 3 continents to discuss the possibility of further conversions of other locomotives. These range from miniature locomotives to a 4-8-2+2-8-4 Garrett locomotive. One visitor who has seen many different systems said 'that it is better than anything other oil firing system he had seen or worked with', yet I intend to make it even better!

The locomotive is now lifted for normal winter maintenance. It has been found that the locomotive is a lot more clean with little of the dirt collecting on it which a coal burner has. This has resulted in the bearings and other parts having less wear and tear to them. This may be a small point but it all adds up to greater savings. Nothing detrimental whatsoever has been found on the locomotive and boiler linked to the conversion from coal to oil. All very good news and proving the many sceptics wrong.

During this winter there is a list of jobs to work through to further improve the system beyond the already proven state. Additionally there are further improvements to the lubrication being installed.

In all, the system has worked well and the locomotive has been very reliable while giving an improved working environment to the staff and visitors alike. The locomotive is only 104 years old and it is not possible to compete on the same level as some more modern machines but it does show what is possible to do to locomotives to improve them for today's working conditions. It is essential that this is understood and kept in context. The work I have done today is only part of a long term plan and will be incorporated into further locomotives of a more modern structure in due course.




4 at Clogwyn

4 at Clogwyn

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Rob Dickinson